The StAr-15 Open Source AR15 Upper Receiver Firearm

Luke C.
by Luke C.
The StAr-15 Open Source AR15 Upper Receiver Firearm

Most custom AR builds often start with a purchase of a lower receiver. After that, it’s pretty much picking out and selecting the components you want that will work with your build and assembling everything. But what if you wanted to make a truly custom AR? One that foregoes the conventional terms of what a firearms “part” is? Well, once again, we have our good friend and dedicated reader Stubbs here to show us the way it’s done. Stubbs is proud to introduce his latest DIY creation, the StAr-15 Open Source AR15 Upper Receiver Firearm. The goal of the StAr-15 is to take the general operating principle of the “standard” AR-15 rifle and make it as inexpensive as possible and also avoid any registered firearms parts. Today we’ll be taking a look at the StAr-15 and how Stubbs cobbled this random assemblage of parts into a functioning DIY firearm.

More of Stubbs’ Evil Creations @ TFB:

The StAr-15 Open Source AR15 Upper Receiver Firearm

The StAr-15 Open Source AR15 Upper Receiver Firearm

The StAr-15 was inspired and maybe even blatantly reverse engineered from a Sten I that Stubbs acquired. Some of you clever readers may have already noticed the similarities.

The St-Ar (Sten/Sterling/Stubbs)-(Armalite (Pattern) Rifle 15) is an open source firearm based on an extremely simplified AR15. The BATFE has many times expressed a desire to redetermine what constitutes a firearm to classify an ar15 upper reciever as a regulated part, and some companies upper recievers themselves are already regulated as firearms, making one assembled gun two separate regulated firearms each subject to tax.

After much backlash they rescinded the redefinition of the AR15 as a controlled split reciever firearm and grandfathered all existing firearms of this style.

This is not to say they will heed forever. If at any point they double back feel relieved knowing an AR15 upper will always be avalable in some form in the same manner a lower can be fabricated at home. All you need is your trusty aluminium tube and a 1.250×18 die.

The AR-15 Simplified

As you can see from the photos so far, the StAr-15 looks quite odd but at its core, it’s still functioning off of a direct gas impingement system. It won’t be winning any beauty contests but I don’t think Stubbs set out to make this thing pretty – just cheap. Almost everything found on a regular AR can be found on the StAr-15 with a few notable omissions. First, there is no AR-15 upper/lower or buffer tube. This eliminates the need for an end plate, castle nut, buffer retainer, detents, and takedown pins – basically all the small parts you lose in your garage putting together one in the first place.

The StAr-15 Open Source AR15 Upper Receiver Firearm

Second, there is no forward assist, dust cover, or any of their associated small parts. Lastly, there is no charging handle. In Stubb’s instance, the charging handle has been replaced by a wine cork attached to the top of the gas key. This, according to Stubbs is the only proprietary part.

In as far as the tools needed to put this thing together, all you really need is a Magpul BEV block, and a Wheeler Armorers Wrench for the assembly portion. Other household garage tools are suitable for the rest of the assembly and cutting/finishing you’ll need and in case you couldn’t have guessed yet, you’ll need a 3D printer to get the lower made as well as the Thompson style forward grip.

The lower and upper are drilled and tapped to make use of some standard quarter-inch bolts to hold them together. Honestly, this is quite a simple solution and something a number of other firearms already do in some shape, form or fashion. The only downside to this that I can see is that any administrative cleaning that needs to be done will require the use of a tool to take the upper and lower apart.

Stubbs mentioned that the most expensive tool to accomplish this job outside of what he already had was the purchase of a 1.250×218 die for putting the threads on the tube to fit the barrel nut. Even with this cost rolled into the project, he told me that the entire thing cost less than $350 including parts he already had. Considering he’s using a cheap bolt carrier group, standard government profile barrel, and some other off-the-shelf non-regulated parts, I find this to be extremely impressive. The most unique item on his list is the aluminum pipe which cost about $40 but in reality, it’s much less since Stubbs only had to use a short length of it for this build.

The StAr-15 Open Source AR15 Upper Receiver Firearm
Parts breakdown as presented to me by Stubbs:

The rest of the parts are pretty standard AR-15 stuff which most of you probably have an entire box full of sitting around somewhere in the garage (and if you don’t, you should).

So Does it work?

According to Stubbs, his StAr-15 works pretty great and considering it’s only about $350 worth of stuff and his time, I find that quite the accomplishment. For those wondering, the StAr-15 as configured in the pictures with the Uzi stock, and forward grip weighs in at 6.5lbs so you’re not really gaining anything in the weight department despite there being no charging handle, a stripped down upper receiver and making use of a 3D printed lower. Another downside of the design is the exposed gas tube which travels out of the rear of the barrel nut and directly interfaces with the gas key.

The StAr-15 Open Source AR15 Upper Receiver Firearm

I asked Stubbs if this design lead to a bunch of gas getting spit right in his face when firing it. Since Stubbs is wrong-handed (a lefty), he said that he’s already used to gas getting in his face from the BGC and with the exposed gas key the gas has tended to blow out of the top. What he said in his own words is that “it farts” but what I think he means by this is that it’d be impossible to shoot it without eye protection. Not an optimal design but once again this is a very cheap AR made at home using a combination of hardware store parts and other commonly available and unregulated firearms parts.

The StAr-15 Open Source AR15 Upper Receiver Firearm

If Stubbs really wanted to, he could probably make his own barrel out of a blank which might reduce costs further. He could have also probably 3D printed the handguard, and pistol grip and left out the UZI stock as well to reduce the cost of the build further. I’m just impressed that his cacophony of parts even functions. I’d like to hear your thoughts as I’m sure Stubbs would. What do you think of the StAr-15 rifle? What would you do differently and how would you tackle a project like this if you were trying to make a super inexpensive AR-15? Let us know down in the comments!

More work on the StAr-15 is already being done by what Stubbs calls “co-conspirators” and these efforts are working towards making simplified and substitute parts for the StAr-15 and there might even be some interesting developments being made using the StAr-15. Sneak preview below.

Photo Credit: Reason Arms

All photos (unless otherwise stated) are credited to Stubbs of the TFB Discord.

Luke C.
Luke C.

Reloader SCSA Competitor Certified Pilot Currently able to pass himself off as the second cousin twice removed of Joe Flanigan. Instagram:

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2 of 53 comments
  • Ryfyle Ryfyle on Jun 02, 2022

    AR's can now be made out random stuff. Gas in the face could be solved with a really janky long stroke piston or sheet metal. The AR has now surpassed the AK in "Junk Gun" catagory, which is honestly better.

  • Tirod3 Tirod3 on Jun 03, 2022

    A 1" ID tube for the upper which directly attached a stock is kinda no brainer. Pin the stock whatever and on take down for cleaning it all exits the rear. When you look at the BCG you can easily see incorporating the buffer weights at the back then pinning the bumper on it as one integral unit shortening the hole thing. Stoner did it to break the action for easier field stripping but for a price we don't care.

    A stamped plate or extruded lower could drop the price on that, a stamped bolt together plate lower has been done already. With a drop in trigger kit we don't care about anything but retention of the parts, a sheetmetal chassis for GI parts is also another no brainer. Shorten the pins and nothing will fall out, just like the FCU on a SIG inside the grip unit.

    That means with some ingenuity the grip can move back 3.4" for better finger relief - instead of the dongled up grips they sell. Using a $2 A2 is cheaper than a $25 tacticool commando grip.

    Here's an idea - rotate barrel/gas 45 degrees to the left same with the ejection port and now you could have a direct fit charging handle incorporated, gas directed to the upper left, brass to the upper right. Bolts don't care if how they feed, it's the ground in feed ramp for the barrel extension that orients that. Ima gonna go onna limb and say tightening the barrel extension another 45degrees won't push the headspace too tight even from the factory. Check the twist rate on the thread . . . if it does, ream it. It would be thousandths of an inch.

    A "80%" lower flat plate kit and "80%" upper aluminum tube as a kit AR taking all the GI parts. $80 bucks. And the next step would be an integral upper lower flat kit with a mandrel to bend the upper tube 360 on a bench top "brake press," HK style. With a mag well poly insert to precisely fit. (Which gives rise to the sheet metal AR10 with the "discontinuities" eliminated - a truly universal AR10.)

    Work in a CNC shop for awhile this stuff isn't rocket surgery. What's missing is that most Americans don't now - they are untrained in the use of machinery and fabrication even more than never having served - 1 in 100 now.